Douglasite is a mineral with the formula 2kcl • fecl2 • 2h2o. calculate the mass percent of douglasite in a 455.0-mg sample if it took 37.20 ml of a 0.1000 m agno3 solution to precipitate all the cl2 as agcl. assume the douglasite is the only source of chloride ion.

The mass percentage is 63.3%

Explanation:

First we need to know how much of the AgNO3 we are using to precipitate the chloride, for this we use:

(37.2 ml * 0.1 M)/1000 ml = 0.00372 moles of AgNO3 which means 0.00372 moles of silver.

the relation between Ag and Cl in the precipitation is 1:1, so we can determine that in our sample we have 0.00372 moles of Cl- and in grams we have 131 mg.

Now we need to know how much of the Douglasite is actually chloride. For that we calculate the molar mass:

Mr = 2*39 + 4*35.45 + 55.85 + 2*18 = 311.65 g/mole

Of that 311.65 grams, 141.8 are Cl. So we could calculate how much of the sample is actual Douglasite:

141.8 g Cl --> 311.65 g Douglasite

0.131 g Cl --> x  = 0.288 g douglasite.

The sample is 0.455 and represents 100 %

Then, the 288 mg of douglasite is the 63.3 %

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms